Many analytic systems incorporate fluid switching valves for controlling fluid flow. An example is the use of rotary shear valves in some chromatography systems. In such chromatography systems, the rotary shear valves are typically employed for the purpose of introducing a sample (analyte) into a mobile phase stream (carrier fluid), which then carries the sample into a chromatography column.
Rotary shear valves generally consist of a rotor and a stator, which seal and wear against each other. The rotor, which is typically a softer wearing part, rotates against the stator, which is typically a harder part that exhibits less wear. As a consequence of the rotation of the rotor against the mating stator, it is common for material to begin to wear off the rotor. The wear rate of the rotor is often not uniform, since travel distance (a main contributor to wear) is based on distance from the center of rotor and angular movement. The resulting wear differences can reduce the operational life of the valve.